Liquid Crystal Device

ABSTRACT

A liquid crystal device, comprising, at least, a pair of polarizing elements being disposed so that the transmission axes thereof are perpendicular to each other; a liquid crystal element disposed between the pair of polarizing elements; and voltage applying means for applying a voltage to the liquid crystal element. The liquid crystal element is such that it enables high-speed optical response, and the optical axis azimuth thereof is rotatable in response to the strength and/or direction of an electric field to be applied thereto. The voltage applying means is capable of controlling a voltage to be applied from the voltage applying means to the liquid crystal element, in response to the liquid crystal molecular alignment in the liquid crystal material. There is provided a liquid crystal device having a temperature-compensating function so as to achieve a good light-dark ratio.

TECHNICAL FIELD

The present invention relates to a liquid crystal device having areduced temperature dependency, which is suitably usable for variousdisplay devices and the like including an optical shutter device and adisplay.

BACKGROUND ART

In recent years, combined with the progress in technology aiming at aso-called “ubiquitous society”, various needs for the display techniquein general, such as high-speed response, downsizing and high displayquality, are sophisticated. In order to meet these needs, also in thefield of visual display and depiction, the display image processingtechnique such as three-dimensional display, selective invisibility andlight control is rapidly advancing and becoming speeded-up andcomplicated. On the other hand, improvement of the environment relatedto information transfer including optical communication using an opticalfiber cable or the like is promoted, and attempts are being made torealize large-volume high-speed data or information transfer.

In general, in various fields including the field of visual display anddepiction, various mechanical/electrical devices have been heretoforeused as the mechanical switch or shutter mechanism for turning ON/OFFthe light. Out of these devices, a chopper comprising a motor and arotating plate having formed therein a slit, and a mechanical shutterusing a piezoelectric (or electrostrictive) element as the actuator havea simple structure and therefore, are being generally used.

However, a tendency of attaching importance particularly to theproperties suitable for use in the so-called ubiquitous society hasrecently intensified and to cope with this trend, as for theswitch/shutter mechanism, a device utilizing an electro-optical effectof, for example, a crystal or a liquid crystal and being excellent interms of downsizing, electric power saving, noise reduction and the likehas come into use.

Furthermore, the above-described device having a conventional mechanicalmechanism is subject to wear in its rocking portion to some degree oranother, and the reliability of the mechanical device inevitably tendsto decrease. Above all, in an application where the device is used atsuch a high speed level as clicking the shutter several tens of times ormore for 1 second, the rocking portion is worn to a significant extent.Of course, fairly severe vibration or noise is generated from the wornportion or the actuator portion such as motor orpiezoelectric/electrostrictive element.

In addition to these problems, in view of downsizing, electric powersaving and the like described above, the trend toward the use of adevice utilizing the electro-optical effect of, for example, a crystalor a liquid crystal is particularly intensifying in recent years.

However, these electro-optical devices are not free of a problem. Forexample, in the case of a PLZT (lead lanthanum-added zirconate titanate)crystal having an electro-optical effect, a driving voltage of severalhundreds of V is necessary for obtaining a sufficiently hightransmittance and depending on the electrode structure of the opticalshutter, breakdown may occur due to the high voltage. Also, by thenature as a crystal, this device has a strong tendency that growth insize is difficult, as compared with a liquid crystal enabling productionof a large-screen display of even 100 inches.

Also, in the case of a device using a TN liquid crystal, the drivingvoltage for operation may be a low voltage of several V, but theresponse speed is as low as approximately several tens of ms andalthough the “rising up” may be improved by applying a high voltage, the“rising down” is not improved, making the high-speed operation to stillremain difficult. In the light of high-speed response and low voltage,use of a ferroelectric liquid crystal may be considered, but theferroelectric liquid crystal has spontaneous polarization and itsdriving disadvantageously requires a large amount of current comparedwith TN liquid crystal and the like. In addition, the site of extinctionposition in a ferroelectric liquid crystal varies depending on thetemperature, and a mechanism to compensate for this change of extinctionposition becomes necessary.

As the method for such temperature compensation, various devices inaccordance with the stable position “slipped” from the original positiondue to the ambient temperature are required, and the construction of theliquid crystal device or optical shutter inevitably becomes complicated.Known examples of the device or method used for adjustment to the stableposition include a mechanical method of adjusting the position of apolarizing device or surface-stabilized ferroelectric liquid crystaldisplay device (see, JP-A (Japanese Unexamined Patent Publication) No.62-204229), a method of inserting a surface-stabilized ferroelectricliquid crystal device and a liquid crystal device having the sametemperature dependency between polarizing devices, thereby canceling thetemperature dependency (see, JP-A No. 4-186230), and a method of,instead of the above-described liquid crystal device having the sametemperature dependency, inserting a compensation device that performspositioning or the like of the optical axis azimuth of a ½ wavelengthplate in accordance with the temperature dependency of thesurface-stabilized ferroelectric liquid crystal device (see, JP-A No.4-186224).

[Patent Document 1] JP-A No. 62-204229

[Patent Document 2] JP-A No. 4-186230 [Patent Document 3] JP-A No.4-186224

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a liquid crystal device(for example, having an optical shutter function) capable of solving theproblem encountered in the prior art.

Another object of the present invention is to provide a liquid crystaldevice having a temperature compensation function capable of achieving agood light/dark ratio condition.

A further object of the present invention is to provide a liquid crystaldevice having a good temperature compensation function substantiallyover the entire operation temperature range.

As a result of intensive studies, the present inventors have found thatit is very effective for achieving the above-described object to use aliquid crystal element capable of rotating the optical axis azimuth inresponse to the strength and/or direction of an electric field to beapplied thereto (for example, a polarization shielding-type smecticliquid crystal (hereinafter referred to as “PSS-LCD”)) and constitute aliquid crystal device by combining the liquid crystal element with apolarizing element and voltage applying means.

The liquid crystal device according to the present invention is based onthe above-mentioned discovery. More specifically, such a liquid crystaldevice comprises, at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are perpendicular to each other,

a liquid crystal element disposed between the pair of polarizingelements, and

voltage applying means for applying a voltage to the liquid crystalelement,

wherein the liquid crystal element comprises, at least, a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates; the optical axis azimuth of the liquid crystal element beingrotatable in response to the strength and/or direction of an electricfield to be applied thereto; and

the voltage applying means is capable of controlling a voltage to beapplied from the voltage applying means to the liquid crystal element,in response to the liquid crystal molecular alignment in the liquidcrystal material.

The present invention also provides a liquid crystal device comprising,at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are crossed with each other,

a liquid crystal element disposed between the pair of polarizingelements, and

angle adjusting means for adjusting the angle between the liquid crystalelement and the polarizing element,

wherein the liquid crystal element comprises, at least, a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates, the optical axis azimuth of the liquid crystal element beingrotatable in response to the strength and/or direction of an electricfield to be applied thereto; and

the angle adjusting means is capable of controlling the angle betweenthe liquid crystal element and the polarizing element in response to theliquid crystal molecular alignment in the liquid crystal material.

The present invention further provides a liquid crystal devicecomprising, at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are perpendicular to each other,

a liquid crystal element disposed between the pair of polarizingelements, and

voltage applying means for applying a voltage to the liquid crystalelement,

wherein the liquid crystal element comprises, at least, a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates; the initial molecular alignment in the liquid crystalelement having a direction which is parallel or almost parallel to thealignment treatment direction for the liquid crystal material; theliquid crystal material showing almost no spontaneous polarization whichis perpendicular to the pair of substrates in the absence of a voltageto be externally applied thereto; and

the voltage applying means is capable of controlling a voltage to beapplied from the voltage applying means to the liquid crystal element,in response to the liquid crystal molecular alignment in the liquidcrystal material.

The present invention further provides a liquid crystal device,comprising at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are perpendicular to each other,

a liquid crystal element disposed between the pair of polarizingelements, and

angle adjusting means for adjusting the angle between the liquid crystalelement and the polarizing element,

wherein the liquid crystal element comprises at least a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates; the initial molecular alignment in the liquid crystalelement having a direction which is parallel or almost parallel to thealignment treatment direction for the liquid crystal material; theliquid crystal material showing almost no spontaneous polarization whichis perpendicular to the pair of substrates in the absence of a voltageto be externally applied thereto; and

the angle adjusting means is capable of controlling the angle betweenthe liquid crystal element and the polarizing element in response to theliquid crystal molecular alignment in the liquid crystal material.

In the liquid crystal device according to the present invention havingthe above-mentioned constitution, a liquid crystal element capable ofrotating the optical axis azimuth in response to the strength and/ordirection of an electric field to be applied thereto can be used withoutany particular limitation, but a “PSS-LCD” (polarization shielding-typesmectic liquid crystal) may preferably be used. In this PSS-LCD, theliquid crystal molecules generally tend to align in the buffingdirection. In the present invention, the quantity of light transmittedthrough the liquid crystal can be controlled, for example, by theelectric field intensity.

Generally, in the case of an analog gradation LCD where liquid crystalmolecules switch their direction in the same plane parallel to thebuffing direction, the transmitted light quantity has temperaturedependency. In the present invention, such temperature dependency can bereduced. In the above-described PSS-LCD device (PSS-LCD), liquid crystalmolecules move quickly and therefore, such temperature dependency tendsto be relatively strong.

In the normal ferroelectric LC that has been conventionally used,alignment of liquid crystal molecules changes only between “two values”(by a voltage exceeding a certain threshold value), whereas in thePSS-LCD, the “tilt angle” of the liquid crystal molecular alignment canbe changed in an analog manner. For this reason, in the presentinvention, PSS-LCD is suitably usable in particular.

In the case of using a liquid crystal element, since the indoortemperature (for example, in a TV station) changes from the outdoortemperature, a so-called “black floating” phenomenon sometimes occurs inthe liquid crystal element due to the temperature change. Such a changeof black (that corresponds, in the change of the transmitted lightquantity, to the “denominator” of a fraction) is known to becomevisually prominent. Colors other than black (colors corresponding to the“numerator” but not to the “denominator” of a fraction) are known toless affect the image even when the transmitted light quantity issomewhat changed.

The present invention includes, for example, the following embodiments.

[1] A liquid crystal device, comprising at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are perpendicular to each other,

a liquid crystal element disposed between the pair of polarizingelements, and

voltage applying means for applying a voltage to the liquid crystalelement,

wherein the liquid crystal element comprises, at least, a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates; the optical axis azimuth of the liquid crystal element beingrotatable in response to the strength and/or direction of an electricfield to be applied thereto; and

the voltage applying means is capable of controlling a voltage to beapplied from the voltage applying means to the liquid crystal element,in response to the liquid crystal molecular alignment in the liquidcrystal material.

[2] A liquid crystal device comprising, at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are crossed with each other,

a liquid crystal element disposed between the pair of polarizingelements, and

angle adjusting means for adjusting the angle between the liquid crystalelement and the polarizing element,

wherein the liquid crystal element comprises, at least, a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates, the optical axis azimuth of the liquid crystal element beingrotatable in response to the strength and/or direction of an electricfield to be applied thereto; and

the angle adjusting means is capable of controlling the angle betweenthe liquid crystal element and the polarizing element in response to theliquid crystal molecular alignment in the liquid crystal material.

[3] A liquid crystal device comprising, at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are perpendicular to each other,

a liquid crystal element disposed between the pair of polarizingelements, and

voltage applying means for applying a voltage to the liquid crystalelement,

wherein the liquid crystal element comprises, at least, a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates; the initial molecular alignment in the liquid crystalelement having a direction which is parallel or almost parallel to thealignment treatment direction for the liquid crystal material; theliquid crystal material showing almost no spontaneous polarization whichis perpendicular to the pair of substrates in the absence of a voltageto be externally applied thereto; and

the voltage applying means is capable of controlling a voltage to beapplied from the voltage applying means to the liquid crystal element,in response to the liquid crystal molecular alignment in the liquidcrystal material.

[4] A liquid crystal device, comprising at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are perpendicular to each other,

a liquid crystal element disposed between the pair of polarizingelements, and

angle adjusting means for adjusting the angle between the liquid crystalelement and the polarizing element,

wherein the liquid crystal element comprises at least a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates; the initial molecular alignment in the liquid crystalelement having a direction which is parallel or almost parallel to thealignment treatment direction for the liquid crystal material; theliquid crystal material showing almost no spontaneous polarization whichis perpendicular to the pair of substrates in the absence of a voltageto be externally applied thereto; and

the angle adjusting means is capable of controlling the angle betweenthe liquid crystal element and the polarizing element in response to theliquid crystal molecular alignment in the liquid crystal material.

[5] A liquid crystal device according to [1] or [2], wherein the liquidcrystal element is capable of rotating the optical axis azimuth inresponse to the strength and/or direction of an electric field to beapplied thereto at a level of 10 to 2 V/μm.

[6] A liquid crystal device according to [1], [2] or [5], wherein theliquid crystal element is capable of high-speed response at a level of 1ms or less.

[7] A liquid crystal device according to any one of [1] to [6], whichhas an optical shutter function.

[8] A liquid crystal device according to any one of [1] to [7], whereinthe liquid crystal molecular alignment in the liquid crystal element canbe represented by the temperature of the liquid crystal material.

[9] A liquid crystal device according to any one of claims [1] to [8],wherein the liquid crystal molecular alignment in the liquid crystalmaterial can be represented by the intensity of output light from one ofthe polarizing elements.

[10] A liquid crystal device, comprising at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are perpendicular to each other,

a liquid crystal element disposed between the pair of polarizingelements, and

light generation means for providing light to the liquid crystalelement,

wherein the liquid crystal element comprises, at least, a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates; the minimum strength of light having passed through theliquid crystal element being measurable in terms of the angle of opticalaxis azimuth.

[11] A liquid crystal device, comprising at least:

a pair of polarizing elements being disposed so that the transmissionaxes thereof are perpendicular to each other,

a liquid crystal element disposed between the pair of polarizingelements,

rotation means for providing a desired rotation angle to the liquidcrystal element,

light generation means for providing light to the liquid crystalelement, and

light detection means for detecting light having passed through theliquid crystal element,

wherein the liquid crystal element comprises, at least, a pair ofsubstrates and a liquid crystal material disposed between the pair ofsubstrates; the rotation means being rotatable so that the strength oflight having passed through the liquid crystal element becomes minimum,and the angle of the rotation means can be measured in terms of theangle of optical axis azimuth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing the optical axis azimuth andtemperature dependency in the state of an electric field being notapplied in a surface-stabilized ferroelectric liquid crystal.

FIG. 2 is a graph showing one example of the temperature dependency ofthe tilt angle in a surface-stabilized ferroelectric liquid crystal.

FIG. 3 is a graph showing one example of the temperature dependency ofthe rotation angle θ in PSS-LCD.

FIG. 4 is a schematic plan view showing the optical axis azimuth in thestate of an electric field being not applied in PSS-LCD.

FIG. 5 is a schematic plan view and a schematic cross-sectional view,showing the electric field applying direction and the rotation angle androtation direction of the optical axis azimuth in PSS-LCD.

FIG. 6 is a schematic plan view showing the temperature dependency inPSS-LCD.

FIG. 7 is a schematic cross-sectional view showing the light-shieldingstate and light-transmitting state of the optical shutter in PSS-LCD.

FIG. 8 is a schematic cross-sectional view showing the temperaturedependency of the optical shutter in PSS-LCD.

FIG. 9 is a graph showing one example of reduction of the contrast ratiodue to temperature dependency of the optical shutter in PSS-LCD.

FIG. 10 is a schematic plan view showing one example of the method forimproving the temperature dependency by the voltage control in a PSS-LCDoptical shutter.

FIG. 11 is a schematic cross-sectional view showing one example of theoptical shutter by PSS-LCD. FIG. 12 is a schematic cross-sectional viewshowing another example of the optical shutter by PSS-LCD.

FIG. 13 is a schematic plan view showing one example of the principle ofimproving the temperature dependency by the element rotation control ina PSS-LCD optical shutter.

FIG. 14 is a schematic cross-sectional view showing one example of theoptical shutter by PSS-LCD (an example where mechanical driving isutilized).

FIG. 15 is a schematic cross-sectional view showing another example ofthe optical shutter by PSS-LCD (an example where mechanical driving isutilized).

FIG. 16 is a schematic perspective view showing one example of theconstruction for mechanically improving the temperature dependency of anoptical shutter by PSS-LCD.

FIG. 17 is a schematic perspective view showing another example of theconstruction for mechanically improving the temperature dependency of anoptical shutter by PSS-LCD. FIG. 18 shows the results of a workingexample where the temperature dependency is improved by the control ofthe applied voltage to an optical shutter by PSS-LCD.

FIG. 19 is a graph showing one example of the improvement of temperaturedependency by the control of the applied voltage to an optical shutterby PSS-LCD.

FIG. 24 is a schematic perspective view showing one example of theconstruction (measurement system) of components suitable for the exactmeasurement of optical axis azimuth, which is usable in the presentinvention.

FIG. 25 is a schematic perspective view showing one example of thePSS-LCD cell produced in a working example of the present invention.

FIG. 26 is a graph showing one example of the control voltage curveobtained in Example of the present invention.

FIG. 27 is a graph showing one example of the control rotation anglecurve obtained in a working example of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is described in detail below by referring to thedrawings, if desired. In the following description, unless otherwiseindicated, the “parts” and “%” indicating a quantitative ratio are onthe mass basis.

Embodiment 1 of Liquid Crystal Device

In one embodiment of the present invention, the liquid crystal devicecomprises at least a pair of polarizing elements with respectivetransmission axes being perpendicular to each other, a liquid crystalelement disposed between the pair of polarizing elements, and voltageapplying means for applying a voltage to the liquid crystal element. Theliquid crystal element is a liquid crystal element which comprises atleast a pair of substrates and a liquid crystal material disposedbetween the pair of substrates and at the same time, in which the liquidcrystal material can rotate the optical axis azimuth in response to thestrength and/or direction of an electric field to be applied thereto.Furthermore, the voltage applying means is voltage applying meanscapable of controlling a voltage to be applied from the voltage applyingmeans to the liquid crystal element in accordance with the liquidcrystal molecular alignment in the liquid crystal material.

Embodiment 2 of Liquid Crystal Device

In another embodiment of the present invention, the liquid crystaldevice is a liquid crystal device comprising at least a pair ofpolarizing elements being disposed so that the transmission axes thereofare perpendicular to each other, a liquid crystal element disposedbetween the pair of polarizing elements, and angle adjusting means foradjusting the angle between the liquid crystal element and thepolarizing element. The liquid crystal element is a liquid crystalelement which comprises at least a pair of substrates and a liquidcrystal material disposed between the pair of substrates and at the sametime, in which the liquid crystal material can rotate the optical axisazimuth in response to the strength and/or direction of an electricfield to be applied thereto. Furthermore, the angle adjusting means isangle adjusting means capable of controlling the angle between theliquid crystal element and the polarizing element in accordance with theliquid crystal molecular alignment in the liquid crystal material.

(Principle of the Present Invention)

The principle of the present invention is described below by making acomparison with the conventional temperature compensation method, ifdesired (one example of the liquid crystal device).

For example, the following case is described as a practical example ofthe liquid crystal device. As for the stereoscopic image displaytechnique, a display method sometimes called a slit-type integralphotography system is known. In this display method, three-dimensionalimages seen from different viewpoints and disposed like a strip aresequentially displayed, as a result, three-dimensional images at aplurality of different viewpoints produce afterimages within theafterimage time of the human eye and are perceived as a stereoscopicimage.

In this integral photography technique, for sequentially displayingthree-dimensional images disposed like a strip, a strip-shapedhigh-speed optical shutter is used. The pitch of strips is very narrowand at the same degree as the pixel pitch of normal FPD (flat paneldisplay), and a device following a very high-speed shuttering time isrequired to sequentially display a plurality of images in about 1/30seconds that is the afterimage time of the human eye.

For example, when 8 image strips in different fields of view aresequentially displayed in 1/30 seconds, the transmission time becomesabout 4.2 milli-seconds per one strip. In the usage where a high-speedshutter operation is performed in such a micro-region, it is optimal toapply a liquid crystal display technique of performing the image displayby light control similarly in a micro-region. However, for realizing theabove-described transmission time of about 4.2 milli-seconds, a responsespeed with the rise-up time and the rise-down time each being 1milli-second or less is necessary, and this is difficult to realize inthe conventional optical shutters using a general TN liquid crystal.

It is supposed that in the case of using a polymer dispersion liquidcrystal recently developed, a high-speed response of severalmilli-seconds can be obtained, but the liquid crystal viscosity needs tobe reduced by applying a voltage of about 100 V and raising the ambienttemperature to about 100° C. Also, since light is scattered and therebyshielded, the contrast ratio when viewed directly is disadvantageouslylow.

The problem in terms of the response speed is supposed to be solvable bythe use of a surface-stabilized ferroelectric liquid crystal exhibitinghigh-speed response with the rise-up time and rise-down time each beingseveral hundreds of micro-seconds. However, as shown in the schematicplan view of FIG. 1 and in the graph of FIG. 2, in an optical shutter,the bi-stable position and angle (tilt angle) for transmission and lightshielding generally vary depending on the element temperature andtherefore, a mechanism to compensate for such an effect of temperatureis required (in the case of using PSS-LCD).

The technique of a polarization shielding-type smectic liquid crystaldisplay (PSS-LCD) previously proposed by the present applicant (fordetails of this PSS-LCD, for example, Kohyo (National Publication ofTranslated Version) No. 2006-515935 may be referred to) is a techniqueenabling, for example, an electro-optical response in 400 micro-secondsas well as continuous gradation display at a low voltage.

Also, by virtue of good uniformity of alignment as compared with generalferroelectric liquid crystals, the contrast is locally high and in thecase of PSS-LCD, even when fabricated as a large-screen display, thevariation of the optical axis direction in the plane is reduced.

However, the temperature dependency like a surface-stabilizedferroelectric liquid crystal display using the same smectic liquidcrystal is observed also in this PSS-LCD. The graph of FIG. 3 shows oneexample of the temperature dependency of the rotation angle θ when arectangular wave of ±5 V is applied to a PSS-LCD element. As shown fromFIG. 3, it may be understood that compared with the temperaturedependency of the tilt angle of the above-described surface-stabilizedferroelectric liquid crystal, the temperature dependency of the rotationangle θ in PSS-LCD is gentle but the rotation angle is changed by thetemperature change.

In the conventional gradation display PSS-LCD, a PSS-LCD element isdisposed between two polarizing plates (under cross-Nicol arrangement)with respective transmission axes being perpendicular to each other andas shown in FIG. 4, the element is disposed such that the optical axisazimuth at the time of not applying an electric field becomes parallelto the transmission axis of either one polarizing plate. When light ismade to be incident on such a system, light turned into linearpolarization by the first polarizing plate is not subject tobirefringent action of the liquid crystal layer and shielded by thesecond polarizing plate to minimize the transmitted light. As shown inFIG. 5, when an electric field is applied, the rotation angle becomes arotation angle 1 or a rotation angle 2 according to the electric fielddirection and allows light to be transmitted by the birefringent action.

The rotation angle θ is determined by the electric field intensity, andthe transmittance can be controlled by analog gradation. The transmittedlight quantity here is expressed by the following formula (1) and whenthe rotation angle θ is ±45° and Δnd is λ/2, the transmitted lightquantity becomes maximum. Formula (1):

$I = {I_{0} \cdot {\sin^{2}\left( {2\theta} \right)} \cdot {\sin^{2}\left( \frac{{\pi\Delta}\; {nd}}{\lambda} \right)}}$

However, this rotation angle has temperature dependency as describedabove and even with the same electric field intensity, as shown in FIG.6, the right/left rotation angle tends to be small at a high temperatureand be large at a low temperature (that is, as indicated by “Change ofRotation Angle” in FIG. 6, when the element temperature is varied, evenif an electric field to be applied thereto intensity is the same, therotation angle changes). Therefore, even with the same electric fieldintensity, the transmittance may be changed according to the elementtemperature, and the light/dark ratio (contrast ratio) may decrease athigh temperatures.

(Operation Example of Optical Shutter)

The operation in one preferred embodiment of the optical shutter of thepresent invention is described below.

For example, as shown in FIG. 7( a), a PSS-LCD element is disposedbetween two polarizing plates with respective transmission axes beingperpendicular and when out of two directions of electric field to beapplied, an electric field in one direction is applied to make theoptical axis azimuth rotated by a rotation angle θ according to theelectric field intensity to be parallel to the transmission axis of onepolarizing plate, the light is shielded to minimize the transmittedlight. This state is referred to as the “light-shielding state” of theoptical shutter.

Thereafter, as shown in FIG. 7( b), an electric field in the oppositedirection from the “light-shielding state” is applied to rotate theoptical axis azimuth by a rotation angle θ according to the electricfield intensity, as a result, light is transmitted. This state isreferred to as the “light-transmitting state”.

The liquid crystal alignment at these light-transmitting state andlight-shielding state is very excellent as compared with the liquidcrystal alignment in the state of an electric field being not appliedand the transmitted light quantity is more increased in thelight-transmitting state, while raising the light-blocking ratio in thelight-shielding state. However, as shown in FIG. 8, when the elementtemperature is changed in the arrangement state above, even if anelectric field to be applied thereto is the same, the rotation angle ofthe optical axis azimuth of the PSS-LCD element is changed and it islikely that light is leaked in the light-shielding state of FIG. 8( a)and the transmitted light quantity decreases in the light-transmittingstate of FIG. 8( b).

The graph of FIG. 9 showing the temperature dependency when adjustingthe light-shielding state at 30° C. reveals that the contrast ratiodecreases as the temperature rises. In order to solve such reduction ofthe contrast ratio, as shown in the schematic cross-sectional view ofFIG. 10, the element temperature is set to, in the operation temperaturerange, a temperature giving a smallest rotation angle θ of the opticalaxis azimuth, and the optical axis azimuth rotated by the application ofan electric field in one direction out of two electric field directionsis allowed to become parallel to the transmission axis of one polarizingplate (in FIG. 10, the indication “maximum rotation angle” means “amaximum rotation angle at which the optical axis azimuth can beoriginally rotated”).

By setting the system as shown in FIG. 10, even when the temperature ischanged and the rotation angle θ of the optical axis azimuth becomeslarge, the rotation angle θ can be made small by weakening the intensityof the electric field applied, whereby the transmission axis of thepolarizing plate can be agreed with the optical axis azimuth and therotation angle in the light-shielding state and the light-transmittingstate can be made constant.

In the case where the total of right/left rotation angles for thesmallest rotation angle θ in the operation temperature range is 45° ormore, by performing the above-described control, the total of theright/left rotation angles of the optical axis azimuth can be adjustedto 45° in the entire operation temperature range and the transmittedlight quantity in the light-transmitting state can be kept maximum.

(Construction for Adjustment of Rotation Angle θ)

As regards the construction for the adjustment of the rotation angle θ,constructions of apparatuses of FIGS. 11 and 12 and the details of theentire operation are described below.

First, the construction in the schematic side view of FIG. 11 isdescribed as one example.

Referring to FIG. 11, PSS-LCD is disposed between perpendicularlyarranged polarizing plates. To this PSS-LCD, a temperature sensorelement such as thermistor or platinum resistance element is equipped tosequentially acquire the temperature information of PSS-LCD. Theacquired temperature information is compared with the information ofelectric field applied to PSS-LCD with respect to the measuredtemperature, which is recorded in the control part.

An electric field to be applied thereto information recorded in thecontrol part is the information prepared by previously measuring theelectric field giving a minimum transmitted light quantity in thelight-shielding state of the PSS-LCD element and a maximum transmittedlight quantity in the light-transmitting state with respect to themeasured temperature. Accordingly, by controlling the system to apply anelectric field with matched intensity to PSS-LCD, a condition providinga minimum transmitted light quantity in the light-shielding state and amaximum transmitted light quantity in the light-transmitting state canbe always reproduced.

As another example, the construction in the schematic side view of FIG.12 is described. A PSS-LCD element is disposed between perpendicularlyarranged polarizing plates. On the light outgoing side, an opticalsensor element such as photodiode or phototransistor is fixed to allowthe transmitted light to be incident thereinto and sequentially acquiresthe transmitted light quantity information. There is performed afeedback control of judging whether the acquired transmitted lightquantity is a minimum transmitted light quantity at the time oflight-shielding state or a maximum transmitted light quantity at thetime of light-transmitting state, and if the case is not so, changingthe intensity of electric field applied to the PSS-LCD element, therebyacquiring the transmitted light quantity. By employing such aconstruction, the light-shielding state and the light-transmitting statecan be constantly kept in the optimal state.

In practice, when the angle of the optical axis direction and the angleof the transmission axis of the polarizing plate come close, thetransmitted light quantity difference tends to become small, increasingthe difficulty in sensing a small light quantity difference in a largerange as in the case of detecting the light-transmitting state.Therefore, in view of adjustment precision, it is rather preferred toadjust the application of an electric field so as to give a minimumtransmitted light quantity in the light-shielding state. The sameapplies to the measurement of a control voltage to be applied, which ismemorized by a method using also a temperature sensor. As for theoptical sensor and temperature sensor, in view of temporal variation andfrequency of the element temperature change, those having acost-effective response speed may be selected.

In the case where the change of maximum transmitted light quantity inthe light-transmitting state need not be taken into consideration, thetransmitted light quantity in the light-shielding state may be minimizedalso by mechanically adjusting the rotation angle θ. In the case ofdisposing a PSS-LCD element between two perpendicularly arrangedpolarizing plates, a mechanical mechanism shown in FIG. 13( b) ofrotating the PSS-LCD element such that the optical axis azimuth rotatedby the application of an electric field in one direction out of twodirections of electric field to be applied becomes parallel to thetransmission axis of one polarizing plate, or a mechanical mechanismshown in FIG. 13( c) of rotating two polarizing plates while keeping theperpendicular relationship may be employed to thereby minimize thetransmitted light quantity in the light-shielding state (incidentally,in FIG. 13( a), the indication “rotation angle θ reduced due totemperature change” means a “rotation angle θ that has become small dueto temperature change”).

(Rotation Mechanism)

As regards the construction of the rotation mechanism, the constructionof the apparatuses of FIGS. 14 to 16 and the details of the entireoperation are described below.

For example, a method of rotating the polarizing plate by a servo motorshown in FIG. 16, and a method of rotating the element by means of apiezoelectric element may be employed as the rotation mechanism. As oneexample of the rotation angle adjustment in this case, the case of usinga servo motor of FIG. 16 that is one example of the construction in theschematic side view of FIG. 14 is described.

Referring to FIG. 16, a PSS-LCD element is disposed betweenperpendicularly arranged polarizing plates. To this PSS-LCD element, atemperature sensor element such as thermistor or platinum resistanceelement is equipped to sequentially acquire the temperature informationof the PSS-LCD element. The acquired temperature information is comparedwith the angle information of the perpendicularly arranged polarizingplates with respect to the PSS-LCD element for the measured temperature,which is recorded in the control part.

The angle information recorded in the control part is the informationprepared by previously measuring the angle giving a minimum transmittedlight quantity in the light-shielding state of the PSS-LCD element forthe measured temperature. Accordingly, by controlling the rotation ofthe servo motor to tilt the perpendicularly arranged polarizing platesat the matched angle, a condition providing a minimum transmitted lightquantity in the light-shielding state can be reproduced.

As another example, the construction in the schematic side view of FIG.15 is described. A PSS-LCD element is disposed between perpendicularlyarranged polarizing plates. On the light outgoing side, an opticalsensor element such as photodiode or phototransistor is fixed to allowthe transmitted light to be incident thereinto and sequentially acquiresthe transmitted light quantity information. There is performed afeedback control of judging from the acquired transmitted light quantitywhether a minimum transmitted light quantity is provided in thelight-shielding state, and if the case is not so, rotating the PSS-LCDelement by an actuator, thereby again acquiring the transmitted lightquantity. By employing such a construction, the light-shielding statecan be constantly kept in the optimal state.

In the case where the element temperature change is not sharp, thecontrol operation frequency decreases and there arises substantially noproblem in terms of abrasion, vibration and noise due to rocking of themechanical mechanism.

(Utilization of Element Undergoing Displacement of Contour)

In addition to the above-described mechanical system, by utilizing anelement of which contour is displaced depending on the temperature, thepolarizing plate or liquid crystal element can be rotated or tilted atthe same time with temperature measurement.

As one example of the construction utilizing such an element of whichcontour is displaced, the construction in the schematic view of FIG. 17is described. Referring to FIG. 17, a bimetal is utilized as theactuator for rotating the PSS-LCD or polarizing plate in FIG. 14 or 15.The bimetal is an element obtained by laminating together two metalsheets differing in the coefficient of thermal expansion and has aproperty of being deformed according to the temperature. Since thedeformation amount depends on the temperature, this element is used in athermometer or a temperature control device.

Similarly to such a device, by utilizing the temperature-relateddeformation as an actuator, the polarizing plate or PSS-LCD can berotated or tilted at the same time with temperature measurement.

In the schematic view of FIG. 17, the bimetal is disposed to undergo adisplacement due to temperature and thereby move a piston up or down.Even if the polarizing plate or PSS-LCD is rotated by transmitting thismovement directly thereto, because of a difference in the temperaturedependency between the bimetal and the PSS-LCD, the transmitted lightquantity cannot be controlled to the minimum in the light-shieldingstate. For this reason, a temperature dependency curve-converting platethat allows the displacement of the bimetal to correspond to thetemperature dependency curve of PSS-LCD, is inserted between the pistonand the PSS-LCD. By employing such a construction, the transmitted lightquantity in the light-shielding state can be controlled to the minimumwhile completely eliminating an electric signal circuit in thetemperature compensation portion. This method is advantageous in thatthe structure is simple and since an electric circuit-related failurecan be completely eliminated, the reliability is high.

(Manual Adjustment)

In the case where the change of the element temperature occurs at a lowfrequency, the transmitted light quantity in the light-shielding statecan be minimized also by manually rotating and/or tilting the polarizingplate or liquid crystal element while observing the transmitted lightquantity in the light-shielding state with an eye. Furthermore, in thecase where the temperature of the element used is fixed, the transmittedlight quantity in the light-shielding state can be minimized bypreparing a polarizing plate or liquid crystal element previouslyrotated or tilted in agreement with the temperature of the element usedand refixing it according to the temperature of the element used.

The fundamental concept of the above-described liquid crystal deviceaccording to the present invention is to fabricate, for example, aliquid crystal device (for example, having an optical shutter function)construction by utilizing a specific electro-optical response of theliquid crystal material (for example, PSS-LCD) used and thereby enablean optical shutter with high transmittance, high light-blocking ratioand high contrast ratio while keeping the high-speed responsivity. Inthe description above, for the convenience sake, an embodiment usingPSS-LCD is mainly described, but irrespective of PSS-LCD, the method ofthe present invention can be applied as long as the liquid crystalmaterial is a material capable of constituting an electro-opticalelement in which the optical axis azimuth is rotated in response to thestrength and/or direction of an electric field to be applied thereto forapplying the system above of the present invention. From the standpointof more effectively bringing out the effects of the present invention, aliquid crystal material enabling a sufficiently high-speed response timeis preferred.

(Polarizing Element)

As for the polarizing element usable in the present invention, apolarizing element conventionally used for fabricating a liquid crystaldevice can be used without any particular limitation. The shape, size,constituent element and the like thereof are also not particularlylimited.

(Suitable Polarizing Element)

Examples of the polarizing element which can be suitably used in thepresent invention include the following:

π-Cell: Molecular Crystals and Liquid Crystals, Vol. 113, page 329(1984), Phil Bos and K. R. Kehler-Beran

(Liquid Crystal Element)

The liquid crystal element according to an embodiment of the presentinvention comprises a pair of substrates and a liquid crystal materialdisposed between the pair of substrates.

(Liquid Crystal Material)

In the present invention, a liquid crystal material can be used withoutany particular limitation as long as it is a liquid crystal materialcapable of constituting an electro-optical element in which the opticalaxis azimuth is rotated in response to the strength and/or direction ofan electric field to be applied thereto for applying the system of thepresent invention. Whether or not a certain liquid crystal material isusable in the present invention can be confirmed by the following“Confirmation Method for Optical Axis Azimuth Rotation”. Also, in thepresent invention, a liquid crystal material capable of a predeterminedhigh-speed response is suitably usable and whether or not a certainliquid crystal material can response at a sufficiently high speed can beconfirmed by the following “Confirmation Method for Response Time”.

(Confirmation Method for Optical Axis Azimuth Rotation)

In regard to the method for measuring the optical axis azimuth rotationas a liquid crystal element, in the case of disposing a liquid crystalelement in the cross-Nicol arrangement where a polarizer is disposedperpendicularly to an analyzer, when the optical axis agrees with theabsorption axis of the analyzer, the. intensity of transmitted lightbecomes minimum. Accordingly, the angle at which the minimum intensityof transmitted light in the cross-Nicol arrangement is obtained becomesthe angle of optical axis azimuth. At this time, an electric field isnot applied to the liquid crystal element. Using this angle as areference angle, an angle at which the minimum intensity of transmittedlight in the cross-Nicol arrangement is obtained when applying anelectric field to the liquid crystal element is sought for. When anangle giving a minimum intensity upon application of an electric fieldis present and the angle giving a minimum intensity is an angle slippedfrom the reference angle and when the strength or direction of theelectric field is varied and an increase or decrease of the rotationangle in accordance with the variation is observed, it can be confirmedthat the optical axis direction is rotated. As regards the apparatus forconfirmation, similarly to the confirmation method for optical axisazimuth, the rotation can be confirmed, for example, by an apparatushaving a construction of FIG. 24.

(Confirmation Method for Response Time)

In the case where optical axis azimuth rotation is observed in theliquid crystal element, the speed of this rotation comes under theresponse time. A liquid crystal element is disposed at an angle giving aminimum transmitted light quantity in the cross-Nicol arrangement wherea polarizer is disposed perpendicularly to an analyzer, and an electricfield is applied to the liquid crystal element. The optical axis azimuthis rotated upon application of an electric field and therefore, thetransmitted light quantity is changed. The degree of change in thetransmitted light quantity becomes the degree of change in the rotation.Assuming that the transmitted light quantity in the state of an electricfield being not applied is 0% and the transmitted light quantity that ischanged by the application of an electric field and finally reaches asteady state is 100%, the time necessary for the transmitted lightquantity to rise from 10% to 90% when an electric field is applied fromthe state of an electric field being not applied is designated as arise-up response time, and the time necessary for the transmitted lightquantity to drop from 90% to 10% when application of an electric fieldis stopped from the state of an electric field being applied isdesignated as a rise-down response time. For example, in PSS-LCD, therise-up response time and the rise-down response time both are about 400μs. As regards the apparatus for confirmation, similarly to“Confirmation Method for Optical Axis Azimuth”, the response time can beconfirmed, for example, by an apparatus having a construction of FIG.24.

The liquid crystal material which is preferably usable in the presentinvention is a PSS-LC, wherein the molecular initial alignment in theliquid crystal material has an almost parallel direction with respect tothe alignment treatment direction; and the liquid crystal material showssubstantially no spontaneous polarization which is at leastperpendicular to a pair of substrates, under the absence of anexternally applied voltage.

(Molecular Initial Alignment)

In the present invention, in the molecular initial alignment (ororientation) in the liquid crystal material, the major axis of theliquid crystal molecules has an almost parallel direction with respectto the alignment treatment direction for the liquid crystal molecules.The fact that the major axis of the liquid crystal molecules has analmost parallel direction with respect to the alignment treatmentdirection can be confirmed, e.g., by the following manner.

In order to enable the liquid crystal device according to the presentinvention to exhibit a desirable display performance, the angle (thenumber as absolute value) between the rubbing direction and thealignment direction of the liquid crystal molecules, which has beenmeasured by the following method may preferably be 3 degrees or less,more preferably be 2 degrees or less, particularly 1 degree or less.

In a strict sense, it is known that when a polymer alignment film suchas polyimide film is subjected to rubbing, a birefringence is induced inthe polyimide outermost layer, to thereby provide a slow optical axis.Further, in general, it is known that the major axis of the liquidcrystal molecules are aligned in parallel with the slow optical axis.With respect to almost all of the polymer alignment films, it is knownthat a certain gap in the angle occurs between the rubbing direction andthe slow optical axis. In general, the gap is relatively small and maybe about 1-7 degrees.

However, this gap in the angle can be 90 degrees as in the case ofpolystyrene as an extreme example.

Therefore, in the present invention, the angle between the rubbingdirection and the alignment direction of the major axis (i.e., opticalaxis) of the liquid crystal molecules may preferably be 3 degrees orless. At this time, the alignment direction of the major axis of theliquid crystal molecules, and the slow optical axis which has beenprovided in the polymer (such as polyimide) polymer alignment film byrubbing, etc., may preferably be 3 degrees or less, more preferably 2degrees or less, particularly 1 degree or less.

As described above, in the present invention, the alignment treatmentdirection refers to the direction of the slow optical axis (in thepolymer outermost layer) which determines the direction of the alignmentof the liquid crystal molecule major axis.

<Method of Measuring Molecular Initial Alignment State for LiquidCrystal Molecules>

In general, the major axis of liquid crystal molecules is in fairagreement with the optical axis. Therefore, when a liquid crystal panelis placed in a cross Nicole arrangement wherein a polarizer is disposedperpendicular to an analyzer, the intensity of the transmitted lightbecomes the smallest when the optical axis of the liquid crystal is infair agreement with the absorption axis of the analyzer. The directionof the initial alignment axis can be determined by a method wherein theliquid crystal panel is rotated in the cross Nicole arrangement whilemeasuring the intensity of the transmitted light, whereby the angleproviding the smallest intensity of the transmitted light can bedetermined.

<Method of Measuring Parallelism of Direction of Liquid Crystal MoleculeMajor Axis with Direction of Alignment Treatment>

The direction of rubbing is determined by a set angle, and the slowoptical axis of a polymer alignment film outermost layer which has beenprovided by the rubbing is determined by the kind of the polymeralignment film, the process for producing the film, the rubbingstrength, etc. Therefore, when the extinction position is provided inparallel with the direction of the slow optical axis, it is confirmedthat the molecule major axis, i.e., the optical axis of the molecules,is in parallel with the direction of the slow optical axis.

(Spontaneous Polarization)

In the present invention, in initial molecular alignment, thespontaneous polarization (which is similar to the spontaneouspolarization in the case of a ferroelectric liquid crystal) is notgenerated, at least with respect to the direction which is perpendicularto the substrate. In the present invention, the “initial molecularalignment providing substantially no spontaneous polarization is suchthat the spontaneous polarization does not occur” can be confirmed,e.g., by the following method.

<Method of Measuring Presence of Spontaneous Polarization Perpendicularto the Substrate>

In a case where the liquid crystal in a liquid crystal cell has aspontaneous polarization, particularly in a case where a spontaneouspolarization is generated in the substrate direction in the initialstate, namely in the direction perpendicular to the electric fielddirection in the initial state (i.e., under the absence of an externalelectric field), when a low-frequency triangular voltage (about 0.1 Hz)is applied to the liquid crystal cell, the direction of the spontaneouspolarization is reversed from the upper direction into the lowerdirection, or from the lower direction into the upper direction, alongwith the change of the polarity of the applied voltage from positiveinto negative, or from negative into positive. Along with such aninversion, actual electric charge is transported (i.e., an electriccurrent is generated). The spontaneous polarization is reversed, onlywhen the polarity of the applied electric field is reversed. Therefore,there appears a peak-shaped electric current as shown in FIG. 20.

The integral value of the peak-shaped electric current corresponds tothe total quantity electric charges to be transported, i.e., thestrength of the spontaneous polarization. When no peak-shaped electriccurrent is observed in this measurement, the absence of the occurrenceof the spontaneous polarization inversion is directly proved by such aphenomenon.

Further, when a linear increase in the electric current as shown in FIG.21 is observed, it is found that the major axis of the liquid crystalmolecules is continuously or consecutively changed in the molecularalignment direction thereof, depending on the increase in the electricfield intensity. In other words, in this case as shown in FIG. 21, ithas been found that there occurs a change in the molecular alignmentdirection due to induced polarization, etc., depending on the intensityof the applied electric field.

(Substrate)

The substrate usable in the present invention is not particularlylimited, as long as it can provide the above-mentioned specific“molecular initial alignment state”. In other words, in the presentinvention, a suitable substrate can appropriately be selected, in viewof the usage or application of LCD, the material and size thereof, etc.Specific examples thereof usable in the present invention are asfollows.

A glass substrate having thereon a patterned a transparent electrode(such as ITO)

An amorphous silicon TFT-array substrate

A low-temperature poly-silicon TFT array substrate

A high-temperature poly-silicon TFT array substrate

A single-crystal silicon array substrate

(Preferred Substrate Examples)

Among these, it is preferred to use following substrate, in a case wherethe present invention is applied to a large-scale liquid crystal displaypanel.

An amorphous silicon TFT array substrate (PSS-LC material)

The PSS-LC material usable in the present invention is not particularlylimited as long as it can provide the above-mentioned specific“molecular initial alignment state”. In other words, in the presentinvention, a suitable liquid crystal material can appropriately beselected, in view of the physical property, electric or displayperformance, etc. For example, various liquid crystal materials(including various ferroelectric or non-ferroelectric liquid crystalmaterials) as exemplified in a publication of may generally be used inthe present invention. Specific preferred examples of such liquidcrystal materials usable in the present invention are as follows.

(Preferred Liquid Crystal Material Examples)

Among these, it is preferred to use the following liquid crystalmaterial, in a case where the present invention is applied to aprojection-type liquid crystal display.

(Alignment Film)

The alignment film usable in the present invention is not particularlylimited as long as it can provide the above-mentioned specific“molecular initial alignment state”. In other words, in the presentinvention, a suitable alignment film can appropriately be selected, inview of the physical property, electric or display performance, etc. Forexample, various alignment films as exemplified in publications maygenerally be used in the present invention. Specific preferred examplesof such alignment films usable in the present invention are as follows.

Polymer alignment film: polyimides, polyamides, polyimide-imides

Inorganic alignment film: SiO2, SiO, Ta205, etc.

(Preferred Alignment Film Examples)

Among these, it is preferred to use the following alignment film, in acase where the present invention is applied to a projection-type liquidcrystal display.

Inorganic Alignment Films

In the present invention, as the above-mentioned substrates, liquidcrystal materials, and alignment films, it is possible to use thosematerials, components or constituents corresponding to the respectiveitems as described in “Liquid Crystal Device Handbook” (1989), publishedby The Nikkan Kogyo Shimbun, Ltd. (Tokyo, Japan), as desired.

(Other Constituents)

The other materials, constituents or components, such as transparentelectrode, electrode pattern, micro-color filter, spacer, and polarizer,to be used for constituting the liquid crystal display according to thepresent invention, are not particularly limited, unless they are againstthe purpose of the present invention (i.e., as long as they can providethe above-mentioned specific “molecular initial alignment state”). Inaddition, the process for producing the liquid crystal display devicewhich is usable in the present invention is not particularly limited,except the liquid crystal display device should be constituted so as toprovide the above-mentioned specific “molecular initial alignmentstate”. With respect to the details of various materials, constituentsor components for constituting the liquid crystal display device, asdesired, “Liquid Crystal Device Handbook” (1989), published by TheNikkan Kogyo Shimbun, Ltd. (Tokyo, Japan) may be referred to.

(Means for Realizing Specific Initial Alignment)

The means or measure for realizing such an alignment state is notparticularly limited, as long as it can realize the above-mentionedspecific'molecular initial alignment state”. In other words, in thepresent invention, a suitable means or measure for realizing thespecific initial alignment can appropriately be selected, in view of thephysical property, electric or display performance, etc.

The following means may preferably be used, in a case where the presentinvention is applied to a large- sized TV panel, a small-sizehigh-definition display panel, and a direct-view type display.

(Preferred Means for Providing Initial Alignment)

According to the present inventors' investigation and knowledge, theabove-mentioned suitable initial alignment may easily be realized byusing the following alignment film (in the case of baked film, thethickness thereof is shown by the thickness after the baking) andrubbing treatment. On the other hand, in ordinary ferroelectric liquidcrystal displays, the thickness of the alignment film 3,000 A (angstrom)or less, and the strength of rubbing (i.e., contact length of rubbing)0.3 mm or less.

Thickness of alignment film: preferably 4,000 A or more, more preferably5,000 A or more (particularly, 6,000 A or more)

Strength of rubbing (i.e., contact length of rubbing): preferably 0.3 mmor more, more preferably 0.4 mm or more (particularly, 0.45 mm or more)

The above-mentioned alignment film thickness and strength of rubbing maybe measured, e.g., in a manner as described in Production Example 1appearing hereinafter

Usable PSS-LCD; Another Embodiment 1

According to another embodiment, there is provided:

a liquid crystal device (i.e., PSS-LCD) comprising: at least, a pair ofsubstrates; a liquid crystal material disposed between the pair ofsubstrates; and a pair of polarizing films disposed on the outside ofthe pair of substrates; wherein one of the pair of polarizing films hasa molecular initial alignment which is parallel or almost parallel withthe alignment treatment direction for the liquid crystal material; theother of the pair of polarizing films has a polarizing absorptiondirection which is perpendicular to the alignment treatment directionfor the liquid crystal material; and, the liquid crystal device shows anextinction angle under the absence of an externally applied voltage.

The liquid crystal display according to such an embodiment has anadvantage that the extinction position thereof does not substantiallyhave a temperature dependency, in addition to those as described above.

Therefore, in this embodiment, it is possible to make the temperaturedependency of the contrast ratio relatively small.

In the above-mentioned relationship wherein the polarizing absorptionaxis direction of the polarizing film is substantially aligned with thealignment treatment direction of the liquid crystal material, the anglebetween the polarizing absorption axis direction of the polarizing filmand the alignment treatment direction of the liquid crystal material maypreferably be 2 degrees or less, more preferably 1 degree or less,particularly 0. 5 degree or less.

In addition, the phenomenon that the liquid crystal device shows anextinction position under the absence of an externally applied voltagemay be confirmed, e.g., by the following method.

<Method of Confirming Extinction Position>

A liquid crystal panel to be examined is inserted between a polarizerand an analyzer which are arranged in cross-Nicole relationship, and theangle providing the minimum light quantity of the transmitted light isdetermined while the liquid crystal panel is being rotated. The thusdetermined angle is the angle of the extinction position.

Usable PSS-LCD; Another Embodiment 2

According to a further embodiment, there is provided: a liquid crystaldevice (i.e., PSS-LCD) comprising: at least, a pair of substrates; and aliquid crystal material disposed between the pair of substrates; whereinthe current passing through the pair of substrates shows substantiallyno peak-shaped current, when a continuously and linearly changingvoltage waveform is applied to the liquid crystal device.

The current passing through the pair of substrates does notsubstantially show a peak-shaped current, under the application of avoltage waveform of which strength is continuously and linearly changed,may be confirmed, e.g., by the following method.

In this embodiment, “the current does not substantially show apeak-shaped current” means that, in the liquid crystal moleculealignment change, the spontaneous polarization does not participate inthe liquid crystal molecule alignment change, at least in a directmanner. The liquid crystal display according to such an embodiment hasan advantage, in addition to those as described above, that it enablessufficient liquid crystal driving, even in a device having the lowestelectron mobility such as amorphous silicon TFT array device amongactive driving devices.

Even when the liquid crystal per se can exhibit a considerably highdisplay performance, if the capacity thereof is relatively large, it isdifficult to drive such a liquid crystal by using an amorphous siliconTFT array device having a limit on the electron mobility. As a result,it is actually impossible to provide high-quality display performance.Even in this case, in view of the ability of driving the liquid crystal,it is possible to provide sufficient display performance, by usinglow-temperature polysilicon and high-temperature polysilicon TFT arraydevices having a lager electron mobility than amorphous silicon; orsingle crystal silicon (silicon wafer) capable of providing the maximumelectron mobility.

On the other hand, the amorphous silicon TFT array is economicallyadvantageous in view of the production cost. Further, when the size ofthe panel is increased, the economic advantage of the amorphous siliconTFT array is much greater than the other types of active devices.

<Method of Confirming Peak-Shaped Current>

A triangular wave voltage having an extremely low frequency of about 0.1Hz is applied to a liquid crystal panel to be examined. The liquidcrystal panel would sense such an applied voltage so that a DC voltageis increased and decreased almost linearly. When the liquid crystal inthe panel shows a ferroelectric liquid crystal phase, the opticalresponse, and charge transfer state are dependent on the polarity of thetriangular wave voltage, but not substantially dependent on the crestvalue (or peak-to-peak value) of the triangular wave voltage. In otherwords, **due** to the presence of the spontaneous polarization, thespontaneous polarization of the liquid crystal is coupled with theexternally applied voltage, only when the polarity of the appliedvoltage is changed from negative to positive, or from positive tonegative. When the spontaneous polarization is reversed, electriccharges are temporarily transferred so as to generate a peak-shapedelectric current in the inside of the panel. On the contrary, if thereverse of the spontaneous polarization does not occur, no peak-shapedelectric current is observed, and the current shows a monotonousincrease, decrease or a constant value.

Therefore, the polarization of the panel may be determined by applying alow-frequency triangular wave voltage to the panel and precisely**measuring** the resultant current, to thereby determine the profile ofthe current wave form.

Usable PSS-LCD; Another Embodiment 3

According to a further embodiment of the present invention, there isprovided: a liquid crystal device (i.e., PSS-LCD) wherein the liquidcrystal molecular alignment treatment for the liquid crystal material isconducted in conjunction with a liquid crystal molecular alignmentmaterial providing a low surface pre-tilt angle.

In this embodiment, the pre-tilt angle may preferably be 1.5 degrees orless, more preferably 1.0 degree or less (particularly 0.5 degree orless). The liquid crystal display according to such an embodiment has anadvantage, in addition to those describe above, that it can provideuniform alignment in a wide area, and a wide view angle.

The reason why the wide view angle is provided is as follows.

In the liquid crystal molecule alignment according to the presentinvention, liquid crystal molecules may be moved within cone-likeregions, and the electro-optical response thereof does not remain in thesame plane.

Generally, when such molecular movement out of the plane is caused, theincidence angle dependency of birefringence occurs, and the viewingangle is narrowed. However, in the liquid crystal molecule alignmentaccording to the present invention, the molecular optical axis of liquidcrystal molecules may always be moved in the clockwise orcounter-clockwise direction, symmetrically and at a high-speed, withrespect of the top of cones, as shown in FIG. 22. Due to the high-speedsymmetrical movement, an extremely symmetrical image may be obtained asa result of time-averaging.

Therefore, with respect to the **view** angle, this embodiment canprovide images having high symmetry and a small angle dependency.

Usable PSS-LCD; Another Embodiment 4

According to a further embodiment of the present invention, there isprovided: a liquid crystal device (i.e., PSS-LCD) wherein the liquidcrystal material shows Smectic A phase to the ferroelectric liquidcrystal phase sequence.

In this embodiment, the phenomenon that the liquid crystal material hasa “Smectic A phase to the ferroelectric liquid crystal phase sequence”can be confirmed, e.g., by the following method. The liquid crystaldisplay according to such an embodiment has an advantage, in addition tothose as described above, that it can provide a higher upper limit ofthe storage temperature therefor. More specifically, in a case where theupper limit of the storage temperature for the liquid crystal display isintended to be determined, even when the temperature exceeds thetransition temperature for the ferroelectric liquid crystal phase toSmectic A phase, it can return to the ferroelectric liquid crystal phaseso as to restore the initial molecular alignment, unless the temperatureexceeds the transition temperature for the smectic A phase tocholesteric phase.

<Method of Confirming Phase Transition Sequence>

The phase transition sequence of the smectic liquid crystal may beconfirmed as follows.

Under a cross Nicole relationship, the temperature of a liquid crystalpanel is lowered from the isotropic phase temperature. At this time, thebuffing direction is made in parallel with the analyzer. As a result ofthe observation by a polarizing microscope, a birefringence changewherein a firework-like shape is changed into a round shape is firstmeasured. When the temperature is further decreased, an extinctiondirection occurs in parallel with the buffing direction. When thetemperature is further decreased, and the phase is converted into aso-called ferroelectric liquid crystal phase. In this phase, when thepanel is rotated by an angle of 3-4 degree around in the vicinity of theextinction position, it is found that the transmitted light intensity isincreased when the position is outside of the extinction position, alongwith a decrease in the temperature.

Herein, it is possible to confirm the helical pitch of a ferroelectricliquid crystal phase and the panel gap of the substrates, e.g., by thefollowing method.

<Method of Confirming Helical Pitch>

In a cell having substrates which have been buffed so as to providealignment treatments in parallel with each other, a liquid crystalmaterial is injected between panels having a cell gap which is at leastfive times the expected helical pitch. As a result, a striped patterncorresponding to the helical pitch appears in the display surface.

<Method of Confirming Panel Gap>

Before the injection of a liquid crystal material, the panel gap may bemeasured by using a liquid crystal panel gap measuring device utilizinglight interference.

(Measuring Method for Optical Axis Azimuth Angle and Construction ofApparatus)

In regard to the method for exactly measuring the optical axis azimuthas a liquid crystal element, in the case of disposing a liquid crystalelement in the cross-Nicol arrangement where a polarizer is disposedperpendicularly to an analyzer, when the optical axis agrees with theabsorption axis of the analyzer, the intensity of transmitted lightbecomes minimum. Accordingly, the angle at which the minimum intensityof transmitted light in the cross-Nicol arrangement is obtained becomesthe angle of optical axis azimuth. Example of the measuring apparatusinclude a polarizing microscope equipped with a photodetection elementsuch as PMT (photomultiplier tube) in the tube part.

The schematic perspective view of FIG. 24 shows one example of theconstruction of components suitable for the exact measurement of opticalaxis azimuth. The polarizer and analyzer of the polarizing microscopeare laid in the cross-Nicol arrangement, a liquid crystal element to bemeasured is disposed on the sample stage by arranging the referenceangle to be the same as the absorption axis angle of the analyzer, andthe sample stage is rotated to make minimum the light quantity detectedby PMT. The angle of the sample stage here becomes the optical axisazimuth angle with respect to the reference angle of the liquid crystalelement.

Hereinbelow, the present invention will be described in more detail withreference to specific Production Examples and Examples.

EXAMPLES Production Example 1

Using commercially available FLC mixture material (Merck: ZLI-4851-100),photo-curable liquid crystalline material (Dai-Nippon Ink Chemicals:UCL-001), and photo initiator material (Merck: Darocur 1173), based onJP-A H11-21554 (Japanese Paten Appln. H09-174463), PS- V-FLCD panel wasfabricated. The mixture had 93 mass % of ZLI-4851-100 FLC mixture, 6mass % of UCL-001, and 1 mass % Darocur 1173.

The substrate used herein was a glass substrate (borosilicate glass,thickness 0.7 mm, size: 50 mm×50 mm; available from Nano Loa Inc.)having thereon an ITO film.

The polyimide alignment film was formed by applying a polyimidealignment material by use of a spin coater, then preliminarily bakingthe resultant film, and finally baking the resultant product in a cleanoven. With respect to the details of the general industrial procedure tobe used herein, as desired, a publication “Liquid Crystal DisplayTechniques”, Sangyo Tosho (1996, Tokyo), Chapter 6 may be referred to.

For the liquid crystal molecular alignment material, RN-1199 (NissanChemicals Industries) was used as 1 to 1.5° of pre-tilt angle alignmentmaterial. Thickness of the alignment layer as cured layer was set at4,500 A to 5,000 A. The surface of this cured alignment layer was buffedby Rayon cloth (mfd. by Yoshikwa Kako, trade name 19RY) in the directionof an angle of 30 degrees to center line of the substrate shown in FIG.23. The contact length of the buffing was set to 0.5 mm at bothsubstrates. In FIG. 23, the angle shown in the “laminated panel” is abuffing angle for the laminated panel.

<Buffing Conditions>

Contact length of the buffing: 0.5 mm

Number of buffing: once

Stage moving speed: 2 mm/sec.

Roller rotational frequency: 1000 rpm (R=40 mm)

Silicon dioxide balls with average diameter of 1.6 μm are used asspacer. Obtained panel gap as measured was 1.8 μm. The above mixedmaterial was injected into the panel at the isotropic phase temperatureof 110° C.

After the mixed material was injected, ambient temperature wascontrolled to reduce 2° C. per minute till the mixed material showedferroelectric phase (40° C.).

Then by natural cooling, after the panel reached room temperature, thepanel was applied with +/−10 V, 500 Hz of triangular waveform, 10minutes (by use of a function generator, mfd. by NF Circuit Block Co.,trade name: WF1946F). After 10 minutes voltage application, 365 nm of UVlight was exposed keeping application of the same voltage (by use of aUV light, mfd. by UVP Co., trade name: UVL-56). The exposure power wasset to 5,000 mJ/cm2. With respect to the details of the generalindustrial procedure to be used herein, as desired, a publication“Liquid Crystal Display Techniques”, Sangyo Tosho (1996, Tokyo), Chapter6 may be referred to.

The initial molecular alignment direction of this panel was same withthe buffing direction. The electro-optical measurement of this panelshowed analog gray scale by application of triangular waveform voltage.

With respect to the details of the general industrial procedure to beused herein, as desired, a publication “The Optics of ThermotropicLiquid Crystals”, Taylor and Francis: 1998, London UK; Chapter 8 andChapter 9 may be referred to.

Production Example 2

For the liquid crystal molecular alignment material,

RN-1199 (Nissan Chemicals Industries) was used as 1 to 1.5° of pre-tiltangle alignment material. Thickness of the alignment layer as curedlayer was set at 6,500 A to 7,000 A. The surface of this cured alignmentlayer was buffed by Rayon cloth in the direction of 30 degrees to centerline of the substrate shown in FIG. 23. The contact length of thebuffing was set to 0.5 mm at both substrates. Silicon dioxide balls withaverage diameter of 1.6 μm are used as spacer. Obtained panel gap asmeasured was. 1.8 μm. In this panel, commercially available FLC mixturematerial (Merck: ZLI-4851-100) was injected at the isotropic phasetemperature of 110° C.

After the mixed material was injected, ambient temperature wascontrolled to reduce 1° C. per minute till the FLO material showedferroelectric phase (40° C.). In this slow cooling process, from SmecticA phase to Chiral Smectic C phase (75° C. to 40° C.), +/−2 V, 500 Hz oftriangular waveform voltage was applied. After panel temperature reached40° C., applied triangular waveform voltage was increased to +/−10V.Then using natural cooling, panel temperature was cooled down to roomtemperature with voltage application. The initial molecular alignmentdirection of this panel was same with the buffing direction in most ofthe observed area, however, in a very limited area showed +/−20 deg.shifted from the buffing angle. The electro-optical measurement of thispanel showed analog gray scale switching as ×20 magnification fieldaverage at polarized microscope observation.

In this production example, it was found that too large voltageapplication at the slow cooling process degrades initial FLC molecularalignment. For instance, at the temperature the panel shows Smectic Aphase, over +/−5V voltage is applied, there shows stripe alignmentdefect along with buffing direction. Once this type of defect happens,voltage application at Chiral smectic C phase (the ferroelectric liquidcrystal phase) does not eliminate the defect. The voltage application atthe slow cooling is effective, but its condition should be strictlycontrolled. In these examples showed that at Smectic A phase, up to 1V/μm, from Smectic A phase to 10° C. below the Smectic A to Chiral SmCphase transition temperature, up to 1.5 V/μm, below 20° C. from thephase transition temperature, up to 5 V/μm, then lower than thistemperature, up to 7.5 V/μm are preferred to obtain good result.

Production Example 3

The liquid crystal molecular alignment material, RN-1199 (NissanChemicals Industries) was used as 1 to 1.5 degree of pre-tilt anglealignment material. Thickness of the alignment layer as cured layer wasset at 6,500 A to 7, 000 A. The surface of this cured alignment layerwas buffed by Rayon cloth in the direction of an angle of 30 degrees tocenter line of the substrate shown in FIG. 23. The contact length of thebuffing was set to 0.6 mm at both substrates. Silicon dioxide balls withaverage diameter of 1.8 μm are used as spacer. Obtained panel gap asmeasured was 2.0 μm. In this panel, Naphthalene base FLC materialdescribed in Molecular Crystals and The liquid crystals; “NaphthaleneBase Ferroelectric liquid crystal and Its Electro Optical Properties”;Vol. 243, pp. 77-pp. 90, (1994). was injected at the isotropic phasetemperature of 130° C. This FIE material's helical pitch at roomtemperature was 2.5 μm.

After the material was injected, ambient temperature was controlled toreduce 1° C. per minute from 130° C. to 50° C. which shows ferroelectricphase. In this slow cooling process, from Smectic A phase to ChiralSmectic C phase (90° C. to 50° C.), +/−1 V, 500 Hz of triangularwaveform voltage was applied. After panel temperature reached 50° C.,applied triangular waveform voltage was increased to +/−7V.

Then using natural cooling, panel temperature was cooled down to roomtemperature with voltage application. The initial molecular alignmentdirection of this panel was same with the buffing direction in most ofthe view area.

Only small slight area, +/−17 deg. shifted from the buffing angle wasobserved. The electro-optical measurement of this panel showed analoggray scale switching as an average of the ×20 magnification field atpolarized microscope observation as shown in FIG. 19. In this productionexample, it was also found that the applied voltage waveform during slowcooling was not limited in triangular waveform, but sine waveform,rectangular waveform were also effective to stabilize the initialmolecular alignment parallel to the buffing direction.

The results obtained in the above Examples are summarized in thefollowing Table 1.

TABLE 1 Wrap-up of Production examples Alignment conditions Photo- Pure-Alignment Buffing Temperature sensitive Base FLC tilt layer thicknesscontact reduction Voltage application conditions Example materialmaterial (deg.) (A) length (mm) rate (δ/min) Higher temperature Lowertemperature Ex. 1 Yes ZLI-4851-100 1 5,000 0.5 2 No ±10 V, 500 Hz,Triangular Ref. Ex. 1 Yes ZLI-4851-100 1 200 0.5 2 No ±10 V, 500 Hz,Triangular Ref. Ex. 2 Yes ZLI-4851-100 1 5,000 0.1 2 No ±10 V, 500 Hz,Triangular Ex. 2 No ZLI-4851-100 1 7,000 0.5 1 ±2 V, 500 Hz; Triangular±10 V, 500 Hz, Triangular Ref. Ex. 3 Yes ZLI-4851-100 1 5,000 0.5 5 No±10 V, 500 Hz, Triangular Ref. Ex. 4 No ZLI-4851-100 1 7,000 0.1 1 ±2 V,500 Hz; Triangular ±10 V, 500 Hz, Triangular Ref. Ex. 5 No ZLI-4851-1001 200 0.1 1 ±2 V, 500 Hz; Triangular ±10 V, 500 Hz, Triangular Ref. Ex.6 No ZLI-1851-100 1 200 0.5 1 ±2 V, 500 Hz; Triangular ±10 V, 500 Hz,Triangular Ref. Ex. 7 Yes ZLI-4851-100 6.5 5,000 0.5 2 No ±10 V, 500 Hz,Triangular Ref. Ex. 8 Yes ZLI-4851-100 6.5 200 0.5 2 No ±10 V, 500 Hz,Triangular Ref. Ex. 9 Yes ZLI-4851-100 6.5 5,000 0.1 2 No ±10 V, 500 Hz,Triangular Ex. 3 No Naphthalene 1 7,000 0.6 1 ±1 V, 500 Hz; Triangular±7 V, 500 Hz, Triangular Ref. Ex. 10 No Naphthalene 1 600 0.2 1 ±1 V,500 Hz; Triangular ±7 V, 500 Hz, Triangular Ref. Ex. 11 No Naphthalene 17,000 0.2 1 ±1 V, 500 Hz; Triangular ±7 V, 500 Hz, Triangular Ref. Ex.12 No Naphthalene 1 7,000 0.6 3 No ±7 V, 500 Hz, Triangular

Example 1

One example of the voltage control system is described as a workingexample of the present invention. Using a glass substrate having a sizeof 35 mm×35 mm and a thickness of 0.7 mm, a circular transparentelectrode ITO of 15 mm in diameter was patterned on the glass substrate.As shown in the schematic perspective view of FIG. 25, the glasssubstrates were laminated together by arranging the transparentelectrodes to face each other, whereby a PSS-LCD cell was prepared.

In order to make constant the size of a gap for the liquid crystal layerby laying two glass substrates to face each other, a silica spacerhaving a particle diameter of 1.8 μm was used. The surfaces of two glasssubstrates were coated with polyimide, then baked and further subjectedto buffing such that the buffing directions became parallel whenoverlapping the substrates. Thereafter, the spacer above dispersed inethanol was scattered on the glass substrate on one side at a ratio of100 particles/mm² and after overlapping the two glass substrates byarranging the transparent electrodes to face each other, a two-componentepoxy resin was filled and fixed in the overlapped portion to produce anempty cell.

Into this cell, a liquid crystal material for PSS-LCD (produced by NanoLoa Inc.) was injected at an isotropic phase temperature of 110° C. toproduce a PSS-LCD cell. The angle of the optical axis azimuth of thispanel was confirmed, as a result, the angle of the optical axis azimuthwas almost parallel to the buffing direction.

A rectangular wave voltage of ±5 V with a frequency of 200 Hz wasapplied to the panel obtained above, and the angle at which thetransmitted light quantity became minimum when applying a voltage of −5V, that is, the optical axis azimuth was measured. At this time, theambient temperature was varied from 30 to 60° C. to measure thetemperature dependency of the optical axis azimuth rotation. In themeasured ambient temperature of 30 to 60° C., the rotation angle of theoptical axis azimuth at 60° C. was 21.5° and minimum. This angle becomesthe reference angle for the compensation of temperature dependency.

This PSS-LCD cell was set in the cross-Nicol arrangement where as shownin FIG. 24, a polarizer is disposed perpendicularly to an analyzer. Atthis time, the cell was set such that the absorption axis of theanalyzer became parallel to the reference angle of 21.5°.

In such a construction, the voltage was controlled in accordance withthe curve of FIG. 26 derived from the temperature dependency of theoptical axis azimuth rotation measured above. In other words, this curveis a curve of the voltage at which the transmitted light quantitybecomes minimum with respect to the ambient temperature. The results areshown in FIG. 18. It was confirmed that compared with the case of notcontrolling the voltage at all as in FIG. 9, variation of the contrastratio is distinctly reduced.

Example 2

One example of the control utilizing mechanical rotation in the presentinvention is described below.

Similarly to Example 1, using a glass substrate having a size of 35mm×35 mm and a thickness of 0.7 mm, a circular transparent electrode ITOof 15 mm in diameter was patterned on the glass substrate. As shown inFIG. 25, the glass substrates were laminated together by arranging thetransparent electrodes to face each other, whereby a PSS-LCD cell wasprepared. In order to make constant the size of a gap for the liquidcrystal layer by laying two glass substrates to face each other, asilica spacer having a particle diameter of 1.8 μm was used. Thesurfaces of two glass substrates were coated with polyimide, then bakedand further subjected to buffing such that the buffing directions becameparallel when overlapping the substrates. Thereafter, the spacer abovedispersed in ethanol was scattered on the glass substrate on one side ata ratio of 100 particles/mm² and after overlapping the two glasssubstrates by arranging the transparent electrodes to face each other, atwo-component epoxy resin was filled and fixed in the overlapped portionto produce an empty cell. Into this cell, a liquid crystal material forPSS-LCD (produced by Nano Loa Inc.) was injected at an isotropic phasetemperature of 110° C. to produce a PSS-LCD cell. The angle of theoptical axis azimuth of this panel was confirmed, as a result, the angleof the optical axis azimuth was almost parallel to the buffingdirection.

A rectangular wave voltage of ±5 V with a frequency of 200 Hz wasapplied to the panel obtained above, and the angle at which thetransmitted light quantity became minimum when applying a voltage of −5V, that is, the optical axis azimuth was measured. At this time, theambient temperature was varied from 30 to 60° C. to measure thetemperature dependency of the optical axis azimuth rotation. The resultsare shown in FIG. 27.

This PSS-LCD cell was set in the cross-Nicol arrangement where as shownin. FIG. 24, a polarizer is disposed perpendicularly to an analyzer.Based on the optical axis azimuth when not applying a voltage to thePSS-LCD cell with respect to the absorption axis of the analyzer, therotation angle was controlled by the ambient temperature in accordancewith FIG. 27. The results are shown in FIG. 19. It was confirmed thatsimilarly to Example 1, variation of the contrast ratio is distinctlyreduced compared with the case of not controlling the rotation angle atall as in FIG. 9.

INDUSTRIAL APPLICABILITY

According to the present invention described above, a liquid crystalelement (for example, PSS-LCD) capable of rotating the optical axisazimuth in response to the strength and/or direction of an electricfield to be applied thereto is used and the temperature compensation isperformed utilizing electro-optical characteristic specific to suchliquid crystal display, so that a liquid crystal device reduced in thetemperature dependency while substantially maintaining hightransmittance can be realized.

5. A liquid crystal device according to claim 1, wherein the liquid crystal element is capable of rotating the optical axis azimuth in response to the strength, and/or direction of an electric field to be applied thereto at a level of 10 to 2 V/μm.
 6. A liquid crystal device according to claim 1, wherein the liquid crystal element is capable of high-speed response at a level of 1 ms or less.
 7. A liquid crystal device according to claim 1, which has an optical shutter function.
 8. A liquid crystal device according to claim 1, wherein the liquid crystal molecular alignment in the liquid crystal element can be represented by the temperature of the liquid crystal material.
 9. A liquid crystal device according to claim 1, wherein the liquid crystal molecular alignment in the liquid crystal material can be represented by the intensity of output light from one of the polarizing elements.
 10. A liquid crystal device according to claim 2, wherein the liquid crystal element is capable of rotating the optical axis azimuth in response to the strength and/or direction of an electric field to be applied thereto at a level of 10 to 2 V/μm.
 11. A liquid crystal device according to claim 2, wherein the liquid crystal element is capable of high-speed response at a level of 1 ms or less.
 12. A liquid crystal device according to claim 5, wherein the liquid crystal element is capable of high-speed response at a level of 1 ms or less.
 13. A liquid crystal device according to claim 2, which has an optical shutter function.
 14. A liquid crystal device according to claim 3, which has an optical shutter function.
 15. A liquid crystal device according to claim 4, which has an optical shutter function.
 16. A liquid crystal device according to claim 5, which has an optical shutter function.
 17. A liquid crystal device according to claim 6, which has an optical shutter function.
 18. A liquid crystal device according to claim 2, wherein the liquid crystal molecular alignment in the liquid crystal element can be represented by the temperature of the liquid crystal material.
 19. A liquid crystal device according to claim 3, wherein the liquid crystal molecular alignment in the liquid crystal element can be represented by the temperature of the liquid crystal material.
 20. A liquid crystal device according to claim 4, wherein the liquid crystal molecular alignment in the liquid crystal element can be represented by the temperature of the liquid crystal material.
 21. A liquid crystal device according to claim 5, wherein the liquid crystal molecular alignment in the liquid crystal element can be represented by the temperature of the liquid crystal material.
 22. A liquid crystal device according to claim 6, wherein the liquid crystal molecular alignment in the liquid crystal element can be represented by the temperature of the liquid crystal material.
 23. A liquid crystal device according to claim 7, wherein the liquid crystal molecular alignment in the liquid crystal element can be represented by the temperature of the liquid crystal material.
 24. A liquid crystal device according to claim 2, wherein the liquid crystal molecular alignment in the liquid crystal material can be represented by the intensity of output light from one of the polarizing elements.
 25. A liquid crystal device according to claim 3, wherein the liquid crystal molecular alignment in the liquid crystal material can be represented by the intensity of output light from one of the polarizing elements.
 26. A liquid crystal device according to claim 4, wherein the liquid crystal molecular alignment in the liquid crystal material can be represented by the intensity of output light from one of the polarizing elements.
 27. A liquid crystal device according to claim 5, wherein the liquid crystal molecular alignment in the liquid crystal material can be represented by the intensity of output light from one of the polarizing elements.
 28. A liquid crystal device according to claim 6, wherein the liquid crystal molecular alignment in the liquid crystal material can be represented by the intensity of output light from one of the polarizing elements.
 29. A liquid crystal device according to claim 7, wherein the liquid crystal molecular alignment in the liquid crystal material can be represented by the intensity of output light from one of the polarizing elements.
 30. A liquid crystal device according to claim 8, wherein the liquid crystal molecular alignment in the liquid crystal material can be represented by the intensity of output light from one of the polarizing elements. 